1. Field of the Invention
The present invention relates to an optical waveguide type microplate for use in biochemical testing, clinical testing, and the like.
2. Description of the Related Art
For example, an enzyme-linked immuno adsorbent assay method (ELISA method) adopted in clinical testing uses a microplate made of a glass or synthetic resin substrate on the surface of which a plurality of wells are formed. That is, an antibody is immobilized on the well inner surface of this microplate, and a solution to be tested containing an antigen is placed in this well to cause an antigen antibody reaction. Subsequently, an enzyme-labeled antibody is placed in the well and labeled by combining the antibody with the antigen. In addition, a color reagent is placed in the well and allowed to develop color by causing the reagent to react with the enzyme-labeled antibody. The degree of this color development is proportional to the amount of antigen in the solution to be tested. Accordingly, the antigen amount in the solution to be tested can be detected by measuring the coloration degree by an absorbance method by which light is sent in the direction of depth of the solution which has colored.
The reagent used in the ELISA method described above is expensive. To reduce the testing cost, therefore, it is being demanded to reduce the use amount of reagent. However, in the conventional microplate with which light is incident in the direction of depth of a solution to be tested which has colored, the optical path to the colored solution is shortened if the reagent is reduced and the solution to be tested itself is reduced accordingly. This makes accurate absorbance measurement difficult, leading to a decrease in the detection accuracy.
The present invention provides an optical waveguide type microplate capable of accurately measuring absorbance and hence capable of detecting an antigen, antibody, and the like in a solution to be tested, even if the amount of reagent to be added to the solution is reduced.